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CRYPT_VERIFY_MESSAGE_PARA structure (wincrypt.h)

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The CRYPT_VERIFY_MESSAGE_PARA structure contains information needed to verify signed messages.

Syntax

typedef struct _CRYPT_VERIFY_MESSAGE_PARA {
  DWORD                            cbSize;
  DWORD                            dwMsgAndCertEncodingType;
  HCRYPTPROV_LEGACY                hCryptProv;
  PFN_CRYPT_GET_SIGNER_CERTIFICATE pfnGetSignerCertificate;
  void                             *pvGetArg;
  PCCERT_STRONG_SIGN_PARA          pStrongSignPara;
} CRYPT_VERIFY_MESSAGE_PARA, *PCRYPT_VERIFY_MESSAGE_PARA;

Members

cbSize

Size of this structure in bytes.

dwMsgAndCertEncodingType

Type of encoding used. It is always acceptable to specify both the certificate and message encoding types by combining them with a bitwise-OR operation as shown in the following example:

X509_ASN_ENCODING | PKCS_7_ASN_ENCODING

Currently defined encoding types are:

  • X509_ASN_ENCODING
  • PKCS_7_ASN_ENCODING

hCryptProv

This member is not used and should be set to NULL.

Windows Server 2003 and Windows XP:  A handle to the cryptographic service provider to be used to verify a signed message. The CSP identified by this handle is used for hashing and for signature verification.Unless there is a strong reason for using a specific cryptographic provider, set to zero to use the default RSA or DSS provider.

This member's data type is HCRYPTPROV.

pfnGetSignerCertificate

A pointer to the callback function used to get the signer's certificate context. If NULL, the default callback is used. The default callback tries to get the signer certificate context from the message's certificate store.

An application defined–callback function that gets the signer's certificate can be used in place of the default. It is passed the certificate identifier of the signer (its issuer and serial number) and a handle to its cryptographic signed message's certificate store.

See CryptGetSignerCertificateCallback for the callback functions signature and arguments.

pvGetArg

Argument to pass to the callback function. Typically, this gets and verifies the message signer's certificate.

pStrongSignPara

Optional pointer to a CERT_STRONG_SIGN_PARA structure that contains parameters used for strong signing. If you set this member and the function successfully verifies the signature, the function will then check for a strong signature. If the signature is not strong, the operation will fail and set the GetLastError value to NTE_BAD_ALGID.

Note  You can use the pStrongSignPara member only if CRYPT_VERIFY_MESSAGE_PARA_HAS_EXTRA_FIELDS is defined by using the #define directive before including Wincrypt.h. If CRYPT_VERIFY_MESSAGE_PARA_HAS_EXTRA_FIELDS is defined, you must zero all unused fields.
 
Windows 8 and Windows Server 2012:  Support for this member begins.

Remarks

This structure is passed to the following functions:

Requirements

Requirement Value
Minimum supported client Windows XP [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Header wincrypt.h

See also

CERT_CONTEXT

CERT_INFO

CryptDecryptAndVerifyMessageSignature

CryptVerifyDetachedMessageSignature

CryptVerifyMessageSignature